Assessment of Groundwater Quality for Irrigational Use in Cumbum Valley, Madurai District, Tamilnadu, India

The suitability of groundwater for irrigation uses was assessed in Cumbum valley covering a total area of about 1485.62 km². The study area is located in Uttamapalyam taluk and a small part of Periyakulam Taluk of Madurai district, Tamil Nadu. Fifty five groundwater samples were collected from open wells in the various locations in the study area. The samples were analyzed for major cations and anions and other parameters viz., EC, Kelley's ratio, SAR values, Mg-hazards, HCO₃ and RSC have been worked out to know the suitability of the groundwater for irrigational purpose. Piper trilinear diagram interpretations were made to know the chemical type of the groundwaters. It reveals that the subsurface water is alkaline earth (Ca+Mg) then alkalies (Na+K) type. The groundwater samples fall under class-I of Doneen's classification and use in good to permissible zone according to Wilcox classification. According to the SAR values plotted in the USSL Staff diagram, most of the groundwater samples belong to C₃-S₁ (41.82%) class indicating that the groundwater could be used for all types of crops on soils of medium to high permeability.